01.06.2022
Participants: G. Daniluk, V. Schramm, D. Valuch
Notes
- DI/OT Crate:
- Better to use a metal version for the front panel ESD plug. It ensures good contact with the metal plate, and "pigtail" connection can be then avoided.
- Info: The chosen starpoint is qualified for 50Hz
- Starpoint of earthing cables could be moved to the side wall of the chassis. Today it's on a back panel, which complicates removal of that panel (however, in practice this panel is not meant to be removed once the crate is assembled).
- Chassis structure looks good in terms of shielding -> if properly done the chassis can take the full shielding function which results in lower criticality for cables inside
- For the ribbon cables inside the crate, the closer they are to the metal plate the better
- BNC/Coax looks like it is isolated to the chassis which may lead to coupling of external disturbances through relays to inside the chassis -> Better to connect outer BNC to chassis
- Regarding the usage of two backplanes (main + 2x power) no particularly negative effect is seen
- Fan tray connector: shielded cable is recommended which is to be connected with the front panel. The shorter this cable is, less noise it will pick up.
- In addition it would be beneficial to ensure that the cables (especially ribbon cables) won't touch the relay
- If the fan tray is not connected in operation there is the possibility of coupling to the backplane through the ribbon cable -> therefore and in general it is advised to guide the cables inside close to the chassis (e.g. close to the metal plate that divides the front-panel space from the PSU space).
- Profinet FMC:
- For the 2 ethernet connectors it would be good to use a component with finger contact for a good connection to the front panel
- Also a good connection of the front panel to a carrier front panel should be ensured to keep the path (connector->finger contacts->front panel->chassis) as short as possible - FMC EMC gaskets that are already used are good solution to that.
- Good practice to verify the often fine gaps between the chassis polygon and other power/GND polygons. During tests often sparks are seen between one and another.
- In general keep paths as short as possible and route currents away to the front panel as soon as possible
- Electromagnetic gaskets to be used for the front panel connection
- nanoFIP FMC:
- Regarding the front panel and the SUB-D connector the same applies as for the Profinet FMC - SUB-D connector should be well touching an FMC front panel
- Fan tray PCB:
- SUB-D connector to be connected to the chassis
- Radtol SB: (schematics not thoroughly pre-studied by Daniel)
- Nothing particular detected on the design
- Nonrad SB: (schematics not thoroughly pre-studied by Daniel)
- No problem seen for the SFP cage which has contact fingers and usually a good connection
- It should be made use of the existing mechanical anchors of the FMC mounting for a good chassis connection
- The lower point of the FMC screw connection (next to the "DI/OT" writing) can be improved for a better connection with the chassis polygon
- Very good that existing SI simulations have been performed
- RaToPUS:
- No particular review yet performed, but it has been good to collaborate closely with SY-EPC
- Already performed individual EMC tests can or should be repeated with the ongoing new design